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GeoEd: An African GIFT Experience

9 Apr

This year the EGU embarked on a new journey into Africa to deliver its renowned Geosciences Information for Teachers (GIFT) programme to teachers in South Africa and neighbouring countries in collaboration with UNESCO and the European Space Agency (ESA). The topic: Climate Change and Human Adaptation. Jane Robb reports on the week’s events…

Set in ‘the windy city’ of Port Elizabeth (or PE if you’re local), in stunning 28°C sun, complimentary blue skies and a dash of wind, we made our way to the Nelson Mandela Metropolitan University’s (NMMU) Missionvale Campus to begin the proceedings. Missionvale Campus is situated just outside Port Elizabeth, in the heart of surrounding communities. The campus is intricately connected to these communities, with a commitment to supporting the development of those local to Port Elizabeth through school education and lifelong learning – making it the ideal location for the workshop.

All of us outside the front of NMMU’s Missionvale Campus. Credit: Jane Robb

All of us outside NMMU’s Missionvale Campus. (Credit: Jane Robb)

We were welcomed by Thoko Mayekiso, the Deputy Vice-Chancellor for Research and Engagement at NMMU, followed by a short introduction given by the co-organisers Sarah Gaines from UNESCO and Carlo Laj from the EGU, and from our host Moctar Doucouré (from NMMU’s Africa Earth Observation Network – Earth Stewardship Science Research Institute, better known as AEON-ESSRI).

To open the workshop, we had Maarten de Wit (from AEON–ESSRI) discuss the importance of geology in understanding climate change. Maarten put geology and climate change into a South African, and broader African, political and social context. He focused on the African concept of ‘observing the present and considering the past to ponder the future’ – a notion that is summed up in the isiXhosa word Iphakade. Maarten introduced Iphakade in the context of Earth stewardship: scientifically informed, ethical and democratic management of both the physical and living systems of our planet. The Earth is a system, but so is our society. Because our society is reliant on the Earth, it has a responsibility to manage it. Therefore, we need to apply our appreciation of our culture and how it will change in the next 50 years to our understanding of how to manage the Earth system.

Echoing the need for systems thinking in managing climate change, Rob O’Donoghue spoke about the South African school curriculum on climate change. Rob highlighted the need for systems thinking to be integrated as a learning enhancement tool. He also echoed the usefulness of the past in learning about the present, not only in a geological context, but in a social one. Africans have lived through climate variability in the past and have met these challenges with innovative solutions in agriculture, animal husbandry, cooking, sanitation and more. Both applied their perspectives on the importance of understanding the socio-cultural aspects of climate change to teaching. They emphasised the need to help relate climate change to children, and stop it seeming scary and impossible to manage. By using stories, art, music and other culturally informed methods we can make understanding and responding to climate change more manageable for future generations.

During lunch (with amazing live local music providing the background to our delicious South African cuisine) we discussed with the teachers their reactions to the workshop so far. What concerned the teachers most was the need to make climate change accessible to their children without forcing an impossible change on them. In many African countries, including South Africa, people are aware that their daily practices are harming the environment. However, unlike developed countries, these practices are essential to survival on a daily basis. The teachers simplified the issue: environment is directly linked to survival in this part of the world. These people do not have the luxury to change their daily practices. If anything, this highlighted the need for workshops like this, which help teachers find different ways to engage the next generation with climate change in a way that means they can continue to develop.

Sally Dengg explaining an experiment about thermohaline circulation to the teachers. For some of our practicals we had to improvise with materials commonly available to teachers – instead of test tubes we used plastic bottles. (Credit: Jane Robb)

Sally Dengg explaining an experiment about thermohaline circulation to the teachers. For some of our practicals we had to improvise with materials commonly available to teachers – instead of test tubes we used plastic bottles. (Credit: Jane Robb)

Carl Palmer from the South African based Applied Centre for Climate and Earth System Science reiterated this point in his talk on how climate change affects us. He highlighted the fact that poor communities cannot deal with climate change in the way developed countries can. And yet, Africa is a large continent, rich in unique landscapes and biodiversity, with an incredible diversity of people too. As Guy Midgely from the South African Biodiversity Institute also discussed, Africa contains a wealth of natural resources as well as a wealth of variable climates and people. Carl emphasised the need to excite and inspire our children about what Africa has to offer, encouraging them to choose science. Not just geoscience however: we need them to address the issues of sanitation, malnutrition, health and politics in tandem with climate to make a real difference. In other words, rather than a threat, climate change is an opportunity to engage kids with science.

To compliment these insightful approaches to climate change education, the workshop integrated several presentations on the science behind climate change and areas where climate change impacts are being felt, including agriculture (Bernard Seguin), water (Roland Schulze), ocean changes (Jean-Pierre Gattuso), as well as remote sensing of the atmosphere (Michael Verstraete). These presentations opened up the discussion for how to teach children specifically about the scientific aspects of climate change: what happens to these different Earth systems in a changing climate, and how can we transfer this knowledge to children in the classroom? For the teachers, although there was a lot of information packed into a tight curriculum, this was incredibly valuable as it catered directly to the GIFT workshop mantra: reducing the time from research to textbook. These presentations gave teachers the opportunity to hear about the science directly from the scientists.

The World Challenge Game in action. ‘Families’ had to colour in sheets to make money for their countries within a time limit. (Credit: Jane Robb)

The World Challenge Game in action. ‘Families’ had to colour in sheets to make money for their countries within a time limit. (Credit: Jane Robb)

In addition to these presentations, we were also treated to demonstrations and practical exercises by Ian McKay, from the University of the Witwatersrand and the International Geoscience Education Organisation, Sally Dengg from GEOMAR Helmholtz Centre for Ocean Research and Carl Palmer. We experienced interactive discussions, marshmallows and chemical structures, solar cookers, production of carbon dioxide, acidifying oceans and exploding hydrogen balloons. To finish up the workshop, we watched the film Thin Ice and ended with a critical discussion on how the teachers will disseminate what they have learnt to their colleagues, students, communities and councils.

What we were able to take away from the workshop was the need for a paradigm shift in the way we think and educate about climate change in an African context, where the participants helped us understand how to make the global local. Climate change isn’t just a scientific issue; it is implicitly related to people, politics and survival. To engage children with climate change science, we need to develop a systems thinking approach, balancing global responsibilities while maintaining healthy lifestyles and valuing the cultures and perspectives of the very people we are trying to engage.

By Jane Robb (EGU Educational Fellow), Sarah Gaines (UNESCO) and Carlo Laj (Chair of the EGU Education Committee)

Imaggeo on Mondays: Exploring the East African Rift

10 Mar

This week’s Imaggeo on Mondays is brought to you by Alexis Merlaud, an atmospheric scientist from the Belgian Institute for Space Aeronomy. While the wonders of the African atmosphere feature in his photography, the East African Rift has a much bigger tale to tell. Drawing from all aspects of geoscience Alexis shares its story…

Kilimanjaro from Mount Meru. (Credit: Alexis Merlaud, distributed via imaggeo.egu.eu)

Kilimanjaro from Mount Meru. (Credit: Alexis Merlaud, distributed via imaggeo.egu.eu)

This picture shows Kilimanjaro, Africa’s highest mountain, at sunrise. It was taken from Socialist Peak, which marks the top of Mount Meru, some 70 km to the southwest. Both mountains are located in Tanzania and are among the largest stratovolcanoes of the East African Rift Zone. Unlike Kilimanjaro, Meru is active and its most recent eruption occurred in 1910.

Stratovolcanoes, also called composite cones, are built-up by alternating layers of lava flows, pyroclastic rocks, and volcanic ash. During a large eruption, huge quantities of ash and sulphur dioxide can reach the stratosphere, where they can affect the climate for several years, as did the eruptions of Krakatau in 1883 and Pinatubo in 1991. Sulphur dioxide is converted to sulphuric acid droplets, which spread with the ashes throughout the stratosphere. These aerosols screen some of the sunlight, decreasing the average surface temperature by about one degree. The temperature in the stratosphere simultaneously rises by a few degrees, due to the enhanced absorption of sunlight by aerosols.

There is a difference in the tectonic processes associated with these South East Asian volcanoes and the East African Rift: the former are located above a subduction zone while the rift is a divergent boundary.  An example of large volcanic eruption in a divergent zone is the Laki (Iceland) eruption in 1783, which yielded severe meteorological conditions and reduced harvests for several years in Europe. This eruption may have also helped trigger the French Revolution in 1789.

Plate tectonics in East Africa created Kilimajaro and have also played a role in early human evolution, by shaping the local landscape and the long-term climate, thus modifying the environment of our ancestors. East Africa is the area in the world where most of the hominid fossils have been discovered, including Homo sapiens – the oldest fossil record is 200,000 years old and started to move out from Africa 100,000 years ago!

A final thanks: thanks Cristina Brailescu for help climbing Meru and Emmanuel Dekemper for support on editing the picture. 

By Alexis Merlaud, Belgian Institute for Space Aeronomy

Imaggeo is the EGU’s open access geosciences image repository. Photos uploaded to Imaggeo can be used by scientists, the press and the public provided the original author is credited. Photographers also retain full rights of use, as Imaggeo images are licensed and distributed by the EGU under a Creative Commons licence. You can submit your photos here.

Geosciences column: Shifting the O in H2O

28 Feb

Wherever you are in the world’s oceans, you can identify particular bodies of water (provided you have the right equipment) by how salty they are. You can get a feel for how productive that part of the ocean is by measuring a few chemical components in the water column. And, year on year, you will see a recurring pattern in how things like temperature, salinity and oxygen content vary with depth. This last property – the oxygen content – is vital for life in the oceans, but recent decades have seen shifts in the amount available.

There is always more oxygen at the surface than there is at depth. When waves break they mix an abundance of tiny air bubbles into the water, providing oceans with their oxygen supply, which is mixed into the deep through large-scale ocean circulation and storms over winter. At the surface, algae make the most of the abundant light to photosynthesise, beginning the base of the marine food web and adding a little more oxygen to the water in the process. These microscopic plants are eaten by animal plankton (zooplankton), which are, in turn, eaten by other plankton, crustaceans, fish, and a plethora of other predators – none of which contribute to the ocean’s oxygen. Instead, they, and a multitude of microbes, slowly use up more and more of the supply as they respire and there comes a point in the water column where there is no longer enough oxygen for these aerobic animals to survive – the oxygen minimum zone (OMZ).

The surface ocean, where oxygen begins its journey to the deep. (Credit: Anna Lourantou, distributed via imaggeo.egu.eu)

The surface ocean, where oxygen begins its journey to the deep. (Credit: Anna Lourantou, distributed via imaggeo.egu.eu)

What marks the boundary of this zone is dependant not on the properties of the water, but the life that lives there – it is the point when marine organisms experience hypoxic stress, usually an oxygen concentration in the range of 60–120 μmol kg−1. Below this, life in the marine environment is very different indeed. Anaerobic microbes thrive below the OMZ, making the most of life in an environment where there is very little oxygen in each litre of seawater.

The boundary between oxygen-rich water and the OMZ is known as the oxygen limiting zone (OLZ), and during the day many small swimming species take refuge here to avoid their predators. In the Eastern Pacific, you reach the OLZ when there’s 60 μmol kg−1 oxygen in the water, and the OMZ when there’s a mere 20 μmol kg−1.

Waves are key to mixing oxygen into the ocean. When they break at the surface they mix air bubbles into the water, taking oxygen from the atmosphere into the sea. (Credit: NOAA Okeanos Explorer Program)

Waves are key to mixing oxygen into the ocean. When they break at the surface they mix air bubbles into the water, taking oxygen from the atmosphere into the sea. (Credit: NOAA Okeanos Explorer Program)

The depth of the OMZ depends on temperature. Because warmer water is capable of containing less dissolved gas than cold, the OMZ is found at shallower depths in the tropics, and occurs at shallower depths in the summer than it does over winter. Winter weather allows more oxygen to be mixed into the deep ocean as storms break down the sea’s stratification, bringing nutrients to the surface and replenishing supplies closer to the sea floor. However, when there’s a lot of production at the surface (which draws down the oxygen) and the replenishment at depth is slow, large oxygen minimum zones persist from year to year.

Recently though, the upper boundaries of these zones have been shifting to shallower depths, resulting larger hypoxic regions in the ocean. Since the 1960s, the OLZ in the Gulf of Alaska, for example, has shifted some 100 metres shallower. Why?

The oceans are absorbing more heat in response to climate change. Because high temperatures reduce oxygen solubility, they reduce the amount of dissolved oxygen at the surface. The increase in surface heat also creates stronger stratification in the ocean, making it harder for oxygen to be mixed deep into the water column, and reducing dissolved oxygen at depth. Ocean circulation systems are also in a state of change, with systems like the Atlantic meridional overturning circulation in decline. Such changes in ocean circulation will also affect the amount of oxygen that’s mixed into the deep sea.

Atlantic meridional overturning circulation, better known as AMOC. Red arrows show warm water circulation in the upper 1100 m and blue arrows show the southward flow of cold, deep water. (Credit: Smeed et al., 2014)

Atlantic meridional overturning circulation, better known as AMOC. Red arrows show warm water circulation in the upper 1100 m and blue arrows show the southward flow of cold, deep water. (Credit: Smeed et al., 2014)

Working out whether this is part of a long-term trend is a difficult task, as records of deep ocean oxygen only stretch back to 70 years ago. Only a longer record of observations will help determine the trend, but for now we can be sure that shoaling oxygen minimum zones will change the amount of habitat available to species either side of the line between oxygen-rich and oxygen-poor.

By Sara Mynott, EGU Communications Officer

References:

Gilly, W. F., Beman, J. M., Litvin, S. Y., & Robison, B. H.: Oceanographic and biological effects of shoaling of the oxygen minimum zone. Annual Review of Marine Science, 5, 393-420, 2013

Smeed, D. A., McCarthy, G. D., Cunningham, S. A., Frajka-Williams, E., Rayner, D., Johns, W. E., Meinen, C. S., Baringer, M. O., Moat, B. I., Duchez, A., and Bryden, H. L.: Observed decline of the Atlantic meridional overturning circulation 2004–2012, Ocean Sci., 10, 29-38, 2014

Geosciences column: Using tall trees to tot up tropical carbon

5 Feb

Forests in the tropics account for about half the above-ground carbon on Earth and as the trees grow older they are capable of storing more and more. In fact, their carbon-storing potential is so large that they are increasingly being viewed as a means of mitigating climate change. Take, for example, the United Nations effort to reduce degradation and deforestation by assigning value to forest carbon.  But programmes like this can only operate if we can calculate forest carbon stocks effectively.

The first step is to suss out a tree’s dimensions. Biomass directly relates to tree height and trunk diameter, so if you know these two details you can work out the amount of carbon stored in a particular tree. This calculation owes its ease to a lot of hard-collected data on tree dimensions and biomass, which, when combined, produces a neat relationship between the two.

Tropical forest in Martinique. (Credit: Wikimedia Commons user Fameme)

Tropical forest in Martinique. Credit: Wikimedia Commons user Fameme)

You can calculate tree height using a tape measure or using LIDAR. LIDAR, short for Light Detection and Ranging, uses a laser to measure the distance to an object by analysing the amount of light reflected back to a detector. Whether you’re using the high tech method or the tape, you’ll always need a little trigonometry. With a quick calculation you can use the distance to the tree base, the distance to the tree top, and the angle from where you’re standing to the top of the tree to work out its height. There are other ways to work this out if you fancy conducting a garden experiment with your smartphone .

But what if you wanted to work out the biomass of not one tree, ten or a hundred, but an entire forest of them? Trekking your way through the trees to measure each in turn would take an unimaginably long time, not to mention that, by the time you finish, the trees you started with will have grown, changed and increased their biomass to boot.

Is there a more practical method? Yes! Satellites are also capable of using LIDAR to estimate tree height remotely – data can be used to calculate the amount of carbon contained in a tropical forest.

Forest canopy in Peru. (Credit: Geoff Gallice)

Forest canopy in Peru. (Credit: Geoff Gallice)

The method is a treat for the budding biogeoscientist. Here’s how it works:

  1. Head out to your favoured forest and use your field skills to measure the height and diameter of 100 or so trees. This means you can ground-truth your measurements and apply them to the rest of the forest.
  2. Scoop up some satellite data on tree height.
  3. Use the relationship between height and biomass that you gathered from trees in the field to find the biomass of the rest of the forest.

A group of scientists, led by Maria Hunter, set out to understand the uncertainty in these measures of biomass. Provided you have your 100 or so local trees as a reference, the biggest uncertainty lies in determining their height. A whole host of uncertainties enter here: from the method used to grab the data to the obstacles that cause you to both over- (in the case of tape measures) or under- (in the case of LIDAR) estimate the height of a tree. Some of these uncertainties can cause major problems for tree height estimation, particularly when the tree is unusually tall.

Despite these difficulties, Hunter found that values for forest biomass were still rather good. This is because many measurement errors cancel each other out when applying the results to a large area.  What’s more, since the majority of trees are not unusually tall, their contribution to biomass determining difficulties are relatively small, leading to an overall error in biomass estimates of approximately 6%. Not too bad at all.

By Sara Mynott, EGU Communications Officer

Reference

Hunter, M. O., Keller, M., Victoria, D., and Morton, D. C.: Tree height and tropical forest biomass estimation, Biogeosciences, 10, 2013.

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